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Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
FEATURES
* Five differential LVDS output pairs * One differential clock input * CLK and nCLK supports the following input types: LVPECL, LVDS, LVHSTL, SSTL, HCSL * Output frequency range: 98MHz - 160MHz * Input frequency range: 98MHz - 128MHz * VCO range: 490MHz - 640MHz * Cycle-to-cycle jitter: 30ps (maximum) * 3.3V operating supply * 3 bandwidth modes allow the system designer to make jitter attenuation/tracking skew design trade-offs * 0C to 70C ambient operating temperature * Available in both standard and lead-free RoHS compliant packages
GENERAL DESCRIPTION
The ICS874005 is a high performance Differential-to-LVDS Jitter Attenuator designed for HiPerClockSTM use in PCI Express systems. In some PCI Express systems, such as those found in desktop PCs, the PCI Express clocks are generated from a low bandwidth, high phase noise PLL frequency synthesizer. In these systems, a jitter attenuator may be required to attenuate high frequency random and deterministic jitter components from the PLL synthesizer and from the system board. The ICS874005 has 3 PLL bandwidth modes: 200kHz, 400kHz, and 800kHz. The 200kHz mode will provide maximum jitter attenuation, but with higher PLL tracking skew and spread spectrum modulation from the motherboard synthesizer may be attenuated. The 400kHz provides an intermediate bandwidth that can easily track triangular spread profiles, while providing good jitter attenuation. The 800kHz bandwidth provides the best tracking skew and will pass most spread profiles, but the jitter attenuation will not be as good as the lower bandwidth modes. Because some 2.5Gb serdes have x20 multipliers while others have than x25 multipliers, the 874005 can be set for 1:1 mode or 5/4 multiplication mode (i.e. 100MHz input/125MHz output) using the F_SEL pins.
IC S
PLL BANDWIDTH
BW_SEL 0 = PLL Bandwidth: ~200kHz Float = PLL Bandwidth: ~400kHz (Default) 1 = PLL Bandwidth: ~800kHz
The ICS874005 uses ICS 3 rd Generation FemtoClock TM PLL technology to achive the lowest possible phase noise. The device is packaged in a 24 Lead TSSOP package, making it ideal for use in space constrained applications such as PCI Express add-in cards.
BLOCK DIAGRAM
OEA Pulldown F_SELA Pulldown BW_SEL Float 0 = ~200kHz Float = ~400kHz 1 = ~800kHz CLK Pulldown nCLK Pullup QA0
F_SELA 0 /5 (default) 1 /4
PIN ASSIGNMENT
nQB2 nQA1 QA1 VDDO QA0 nQA0 MR BW_SEL VDDA F_SELA VDD OEA 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 QB2 VDDO QB1 nQB1 QB0 nQB0 F_SELB OEB GND GND nCLK CLK
nQA0 QA1
Phase Detector
VCO
490 - 640MHz
nQA1 QB0
F_SELB 0 /5 (default) 1 /4
nQB0 QB1 nQB1 QB2 nQB2
M = /5 (fixed)
ICS874005
24-Lead TSSOP
4.40mm x 7.8mm x 0.92mm package body
F_SELB Pulldown MR Pulldown OEB Pullup
874005AG
G Package Top View
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
Type Output Output Power Output Output Input Description Differential output pair. LVDS interface levels. Differential output pair. LVDS interface levels. Output supply pins. Differential output pair. LVDS interface levels. Inver ting differential feedback output. Active HIGH Master Reset. When logic HIGH, the internal dividers are reset causing the true outputs (nQx) to go low and the inver ted outputs Pulldown (Qx) to go high. When logic LOW, the internal dividers and the outputs are enabled. LVCMOS/LVTTL interface levels. Pullup/ PLL Bandwidth input. See Table 3B. Pulldown Analog supply pin. Frequency select pin for QAx/nQAx outputs. Pulldown LVCMOS/LVTTL interface levels. Core supply pin. Output enable pin for QA pins. When HIGH, the QAx/nQAx outputs are active. When LOW, the QAx/nQAx outputs are in a high impedance Pullup state. LVCMOS/LVTTL interface levels. Pulldown Non-inver ting differential clock input. Pullup Inver ting differential clock input. Power supply ground. Output enable pin for QB pins. When HIGH, the QBx/nQBx outputs are Pullup active. When LOW, the QBx/nQBx outputs are in a high impedance state. LVCMOS/LVTTL interface levels. Frequency select pin for QBx/nQBx outputs. Pulldown LVCMOS/LVTTL interface levels. Differential output pair. LVDS interface levels. Differential output pair. LVDS interface levels.
TABLE 1. PIN DESCRIPTIONS
Number 1, 24 2, 3 4, 23 5, 6 6 7 Name nQB2, QB2 nQA1, QA1 VDDO QA0, nQA0 nFB_OUT MR
8 9 10 11 12 13 14 15, 16 17 18 19, 20 21, 22
BW_SEL VDDA F_SELA VDD OEA CLK nCLK GND OEB F_SELB nQB0, QB0 nQB1, QB1
Input Power Input Power Input Input Input Power Input Input Output Output
NOTE: Pullup and Pulldown refer to internal input resistors. See Table 2, Pin Characteristics, for typical values.
TABLE 2. PIN CHARACTERISTICS
Symbol CIN RPULLUP RPULLDOWN Parameter Input Capacitance Input Pullup Resistor Input Pulldown Resistor Test Conditions Minimum Typical 4 51 51 Maximum Units pF k k
TABLE 3A. OUTPUT ENABLE FUNCTION TABLE
Inputs OEA/OEB 0 1 HiZ Enabled Outputs QAx/nQAx QBx/nQBx HiZ Enabled
TABLE 3B. PLL BANDWIDTH/PLL BYPASS CONTROL
Inputs PLL_BW 0 1 Float PLL Bandwidth ~200kHz ~800kHz ~400kHz
REV. A JANUARY 25, 2006
874005AG
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2
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
4.6V -0.5V to VDD + 0.5 V -0.5V to VDDO + 0.5V 70C/W (0 lfpm) -65C to 150C NOTE: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These ratings are stress specifications only. Functional operation of product at these conditions or any conditions beyond those listed in the DC Characteristics or AC Characteristics is not implied. Exposure to absolute maximum rating conditions for extended periods may affect product reliability.
ABSOLUTE MAXIMUM RATINGS
Supply Voltage, VDD Inputs, VI Outputs, VO Package Thermal Impedance, JA Storage Temperature, TSTG
TABLE 4A. POWER SUPPLY DC CHARACTERISTICS, VDD = VDDA = VDDO = 3.3V5%, TA = 0C TO 70C
Symbol VDD VDDA VDDO IDD IDDA IDDO Parameter Core Supply Voltage Analog Supply Voltage Output Supply Voltage Power Supply Current Analog Supply Current Output Supply Current Test Conditions Minimum 3.135 3.135 3.135 Typical 3. 3 3. 3 3.3 Maximum 3.465 3.465 3.465 85 15 115 Units V V V mA mA mA
TABLE 4B. LVCMOS/LVTTL DC CHARACTERISTICS, VDD = VDDA = VDDO = 3.3V5%, TA = 0C TO 70C
Symbol Parameter VIH Input High Voltage OEA, OEB, MR, F_SELA, F_SELB BW_SEL VIL VIM IIH Input Low Voltage Input Mid Voltage Input High Current OEA, OEB, MR, F_SELA, F_SELB BW_SEL BW_SEL OEA, OEB F_SELA, F_SELB MR, BW_SEL BW_SEL, OEA, OEB MR, F_SELA, F_SELB VDD = VIN = 3.465V VDD = VIN = 3.465V VDD = 3.465V, VIN = 0V VDD = 3.465V, VIN = 0V -150 -5 VDD/2 - 0.1 Test Conditions Minimum 2 VDD - 0.4 -0.3 0.8 0.4 VDD/2 + 0.1 5 150 Typical Maximum VDD + 0.3 Units V V V V V A A A A
IIL
Input Low Current
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
Test Conditions CLK nCLK CLK nCLK VDD = VIN = 3.465V VDD = VIN = 3.465V VDD = VIN = 3.465V VDD = VIN = 3.465V -150 0.15 1.3 VDD - 0.85 V V 5 15 0 A Minimum Typical Maximum 15 0 Units A
TABLE 4C. DIFFERENTIAL DC CHARACTERISTICS, VDD = VDDA = VDDO = 3.3V5%, TA = 0C TO 70C
Symbol IIH IIL VPP Parameter Input High Current Input Low Current
Peak-to-Peak Input Voltage
VCMR Common Mode Input Voltage; NOTE 1, 2 GND + 0.5 NOTE 1: Common mode voltage is defined as VIH. NOTE 2: For single ended applications, the maximum input voltage for CLK, nCLK is VDD + 0.3V.
TABLE 4D. LVDS DC CHARACTERISTICS, VDD = VDDA = VDDO = 3.3V5%, TA = 0C TO 70C
Symbol VOD VOD VOS VOS Parameter Differential Output Voltage VOD Magnitude Change Offset Voltage VOS Magnitude Change 1.2 1.35 Test Conditions Minimum 275 Typical 375 Maximum 485 50 1.5 50 Units mV mV V mV
TABLE 5. AC CHARACTERISTICS, VDD = VDDA = VDDO = 3.3V5%, TA = 0C TO 70C
Symbol fMAX tjit(cc) tsk(o) tR / tF Parameter Output Frequency Cycle-to-Cycle Jitter, NOTE 1 Output Skew; NOTE 2, 3 Output Rise/Fall Time 20% to 80% 300 Test Conditions Minimum 98 15 Typical Maximum 160 30 90 550 52 Units MHz ps ps ps %
odc Output Duty Cycle 48 NOTE 1: This parameter is defined in accordance with JEDEC Standard 65. NOTE 2: Defined as skew between outputs at the same supply voltage and with equal load conditions. Measured at VDDO/2. NOTE 3: These parameters are guaranteed by characterization. Not tested in production.
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
PARAMETER MEASUREMENT INFORMATION
VDD, VDDO VDDA
VDD
3.3V5% POWER SUPPLY Float GND + -
Qx
SCOPE
nCLK
V
PP
LVDS
nQx
Cross Points
V
CMR
CLK
GND
3.3V LVDS OUTPUT LOAD AC TEST CIRCUIT
nQA0, nQA1 nQB0:nQB2 QA0, QA1 QB0:QB2
DIFFERENTIAL INPUT LEVEL
nQx Qx
tjit(cc) = tcycle n -tcycle n+1
1000 Cycles
CYCLE-TO-CYCLE JITTER
80% Clock Outputs
20% tR tF
OUTPUT RISE/FALL TIME
VDD out
DC Input
LVDS
100
VOD/ VOD
out
out
VOS/ VOS
DIFFERENTIAL OUTPUT VOLTAGE SETUP
874005AG
OFFSET VOLTAGE SETUP
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REV. A JANUARY 25, 2006

tcycle n
tcycle
n+1
nQy Qy
tsk(o)
OUTPUT SKEW
nQA0, nQA1 nQB0:nQB2
80% VSW I N G 20%
QA0, QA1 QB0:QB2
t PW
t
PERIOD
odc =
t PW t PERIOD
x 100%
OUTPUT DUTY CYCLE/PULSE WIDTH/PERIOD
VDD out
DC Input
LVDS
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR APPLICATION INFORMATION
POWER SUPPLY FILTERING TECHNIQUES
As in any high speed analog circuitry, the power supply pins are vulnerable to random noise. The ICS874005 provides separate power supplies to isolate any high switching noise from the outputs to the internal PLL. VDD, VDDA, and VDDO should be individually connected to the power supply plane through vias, and bypass capacitors should be used for each pin. To achieve optimum jitter performance, power supply isolation is required. Figure 1 illustrates how a 10 resistor along with a 10F and a .01F bypass capacitor should be connected to each VCCA pin.
3.3V VDD .01F VDDA .01F 10F 10
FIGURE 1. POWER SUPPLY FILTERING
WIRING THE DIFFERENTIAL INPUT TO ACCEPT SINGLE ENDED LEVELS
Figure 2 shows how the differential input can be wired to accept single ended levels. The reference voltage V_REF = VDD/2 is generated by the bias resistors R1, R2 and C1. This bias circuit should be located as close as possible to the input pin. The ratio of R1 and R2 might need to be adjusted to position the V_REF in the center of the input voltage swing. For example, if the input clock swing is only 2.5V and VDD = 3.3V, V_REF should be 1.25V and R2/R1 = 0.609.
VDD
R1 1K Single Ended Clock Input CLK V_REF nCLK C1 0.1u
R2 1K
FIGURE 2. SINGLE ENDED SIGNAL DRIVING DIFFERENTIAL INPUT
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
here are examples only. Please consult with the vendor of the driver component to confirm the driver termination requirements. For example in Figure 3A, the input termination applies for ICS HiPerClockS LVHSTL drivers. If you are using an LVHSTL driver from another vendor, use their termination recommendation.
3.3V 3.3V
DIFFERENTIAL CLOCK INPUT INTERFACE
The CLK /nCLK accepts LVDS, LVPECL, LVHSTL, SSTL, HCSL and other differential signals. Both VSWING and VOH must meet the VPP and VCMR input requirements. Figures 3A to 3D show interface examples for the HiPerClockS CLK/nCLK input driven by the most common driver types. The input interfaces suggested
3.3V 1.8V
Zo = 50 Ohm
Zo = 50 Ohm CLK Zo = 50 Ohm nCLK LVHSTL ICS HiPerClockS LVHSTL Driver R1 50 R2 50
R3 50 LVPECL Zo = 50 Ohm
CLK
nCLK
HiPerClockS Input
HiPerClockS Input
R1 50
R2 50
FIGURE 3A. HIPERCLOCKS CLK/NCLK INPUT DRIVEN ICS HIPERCLOCKS LVHSTL DRIVER
BY
FIGURE 3B. HIPERCLOCKS CLK/NCLK INPUT DRIVEN 3.3V LVPECL DRIVER
BY
3.3V 3.3V 3.3V R3 125 Zo = 50 Ohm CLK Zo = 50 Ohm nCLK LVPECL R1 84 R2 84 HiPerClockS Input R4 125
3.3V 3.3V LVDS_Driv er R1 100 Zo = 50 Ohm Zo = 50 Ohm
CLK
nCLK
Receiv er
FIGURE 3C. HIPERCLOCKS CLK/NCLK INPUT DRIVEN 3.3V LVPECL DRIVER
BY
FIGURE 3D. HIPERCLOCKS CLK/NCLK INPUT DRIVEN 3.3V LVDS DRIVER
BY
RECOMMENDATIONS FOR UNUSED INPUT AND OUTPUT PINS INPUTS: OUTPUTS:
LVCMOS CONTROL PINS: All control pins have internal pull-ups or pull-downs; additional resistance is not required but can be added for additional protection. A 1k resistor can be used. LVDS All unused LVDS output pairs can be either left floating or terminated with 100 across. If they are left floating, we recommend that there is no trace attached.
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
the receiver input. For a multiple LVDS outputs buffer, if only partial outputs are used, it is recommended to terminate the un-used outputs.
3.3V
LVDS DRIVER TERMINATION
A general LVDS interface is shown in Figure 4. In a 100 differential transmission line environment, LVDS drivers require a matched load termination of 100 across near
3.3V LVDS_Driv er + R1 100
-
100 Ohm Differiential Transmission Line
FIGURE 4. TYPICAL LVDS DRIVER TERMINATION
SCHEMATIC EXAMPLE
Figure 5 shows an example of ICS874005 application schematic. In this example, the device is operated at VDD=3.3V. The decoupling capacitor should be located as close as possible to the power pin. The input is driven by a 3.3V LVPECL driver.
VDD = 3.3V
VDDO = 3.3V
Zo = 50 Ohm
+ U1 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 14 13 Zo = 50 Ohm R2 100 nQB2 nQA1 QA1 VDDO QA0 nQAO MR BW_SEL VDDA F_SELA VDD OEA QB2 VDDO QB1 nQB1 QB0 nQB0 F_SELB OEB GND GND nCLK CLK
R1 10
C3 10uF
C4 0.01u
MR BW_SEL F_SELA OEA
F_SELB OEB
Zo = 50 Ohm
+ 874005_tssop24 Zo = 50 Ohm nCLK Zo = 50 Ohm R3 100 -
Zo = 50 Ohm CLK
LVPECL Driv er
R4 50 (U1:23) R6 50
R5 50
(U1:11)
(U1:4)
C5 10uf
C6 .1uf
C7 .1uf
C8 .1uf
FIGURE 5. ICS874005 SCHEMATIC EXAMPLE
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR POWER CONSIDERATIONS
This section provides information on power dissipation and junction temperature for the ICS874005. Equations and example calculations are also provided. 1. Power Dissipation. The total power dissipation for the ICS874005 is the sum of the core power plus the power dissipated in the load(s). The following is the power dissipation for VDD = 3.3V + 5% = 3.465V, which gives worst case results.
* *
Power (core)MAX = VDD_MAX * (IDD_MAX + IDDA_MAX) = 3.465V * (85mA + 15mA) = 346.5mW Power (outputs)MAX = VDDO_MAX * IDDO_MAX = 3.465V * 115mA = 398.48mW
Total Power_MAX = 346.5mW + 398.48mW = 745mW
2. Junction Temperature. Junction temperature, Tj, is the temperature at the junction of the bond wire and bond pad and directly affects the reliability of the device. The maximum recommended junction temperature for HiPerClockSTM devices is 125C. The equation for Tj is as follows: Tj = JA * Pd_total + TA Tj = Junction Temperature qJA = Junction-to-Ambient Thermal Resistance Pd_total = Total Device Power Dissipation (example calculation is in section 1 above) TA = Ambient Temperature In order to calculate junction temperature, the appropriate junction-to-ambient thermal resistance JA must be used. Assuming a moderate air flow of 200 linear feet per minute and a multi-layer board, the appropriate value is 63C/W per Table 6 below. Therefore, Tj for an ambient temperature of 70C with all outputs switching is: 70C + 0.745W * 63C/W = 117C. This is below the limit of 125C. This calculation is only an example. Tj will obviously vary depending on the number of loaded outputs, supply voltage, air flow, and the type of board (single layer or multi-layer).
TABLE 6. THERMAL RESISTANCE JA FOR 24-LEAD TSSOP, FORCED CONVECTION
JA by Velocity (Linear Feet per Minute)
0
Multi-Layer PCB, JEDEC Standard Test Boards 70C/W
200
63C/W
500
60C/W
NOTE: Most modern PCB designs use multi-layered boards. The data in the second row pertains to most designs.
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR RELIABILITY INFORMATION
TABLE 7. JAVS. AIR FLOW TABLE FOR 24 LEAD TSSOP
JA by Velocity (Linear Feet per Minute)
0
Multi-Layer PCB, JEDEC Standard Test Boards 70C/W
200
63C/W
500
60C/W
TRANSISTOR COUNT
The transistor count for ICS874005 is: 1206
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
FOR
PACKAGE OUTLINE - G SUFFIX
24 LEAD TSSOP
TABLE 8. PACKAGE DIMENSIONS
SYMBOL N A A1 A2 b c D E E1 e L aaa 0.45 0 -4.30 0.65 BASIC 0.75 8 0.10 -0.05 0.80 0.19 0.09 7.70 6.40 BASIC 4.50 Millimeters Minimum 24 1.20 0.15 1.05 0.30 0.20 7.90 Maximum
Reference Document: JEDEC Publication 95, MO-153
874005AG
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REV. A JANUARY 25, 2006
Integrated Circuit Systems, Inc.
ICS874005
PCI EXPRESSTM JITTER ATTENUATOR
TABLE 9. ORDERING INFORMATION
Part/Order Number ICS874005AG ICS874005AGT ICS874005AGLF ICS874005AGLFT Marking ICS874005AG ICS874005AG TB D TBD Package 24 Lead TSSOP 24 Lead TSSOP 24 Lead "Lead-Free" TSSOP 24 Lead "Lead-Free" TSSOP Shipping Packaging tube 2500 tape & reel tube 2500 tape & reel Temperature 0C to 70C 0C to 70C 0C to 70C 0C to 70C
NOTE: Par ts that are ordered with an "LF" suffix to the par t number are the Pb-Free configuration and are RoHS complaint.
The aforementioned trademarks, HiPerClockS and FemtoClock are trademarks of Integrated Circuit Systems, Inc. or its subsidiaries in the United States and/or other countries. While the information presented herein has been checked for both accuracy and reliability, Integrated Circuit Systems, Incorporated (ICS) assumes no responsibility for either its use or for infringement of any patents or other rights of third parties, which would result from its use. No other circuits, patents, or licenses are implied. This product is intended for use in normal commercial and industrial applications. Any other applications such as those requiring high reliability or other extraordinary environmental requirements are not recommended without additional processing by ICS. ICS reserves the right to change any circuitry or specifications without notice. ICS does not authorize or warrant any ICS product for use in life support devices or critical medical instruments. 874005AG
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REV. A JANUARY 25, 2006

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